A 65-year-old Bronx man died because of a surgical sponge left in him during open-heart surgery at Montefiore Medical Center, his children claim in a lawsuit.

Peter Rullan would have otherwise survived the October 2007 procedure, alleges the suit, filed in Bronx Supreme Court by his children, Peter and Janice.

After a second surgery, to remove the sponge, Rullan developed an infection and was bedridden until his death, the suit says.

When he sued a month before dying in 2008, the hospital and Dr. David D’Alessandro denied all allegations.